Diversity of structures and functions of oxo-bridged non-heme diiron proteins

Maria Luiza Caldas Nogueira, Anthony J. Pastore, Victor L. Davidson

Research output: Contribution to journalReview articlepeer-review


Oxo-bridged diiron proteins are a distinct class of non-heme iron proteins. Their active sites are composed of two irons that are coordinated by amino acid side chains, and a bridging oxygen that interacts with each iron. These proteins are members of the ferritin superfamily and share the structural feature of a four α-helix bundle that provides the residues that coordinate the irons. The different proteins also display a wide range of structures and functions. A prototype of this family is hemerythrin, which functions as an oxygen transporter. Several other hemerythrin-like proteins have been described with a diversity of functions including oxygen and iron sensing, and catalytic activities. Rubrerythrins react with hydrogen peroxide and rubrerythrin-like proteins possess a rubredoxin domain, in addition to the oxo-bridged diiron center. Other redox enzymes with oxo-bridged irons include flavodiiron proteins that act as O2 or NO reductases, ribonucleotide reductase and methane monooxygenase. Ferritins have an oxo-bridged diiron in the ferroxidase center of the protein, which plays a role in the iron storage function of these proteins. There are also bacterial ferritins that exhibit catalytic activities. The structures and functions of this broad class of oxo-bridged diiron proteins are described and compared in this review.

Original languageEnglish (US)
Article number108917
JournalArchives of Biochemistry and Biophysics
StatePublished - Jul 15 2021
Externally publishedYes


  • Ferritin
  • Flavodiiron protein
  • Hemerythrin
  • Methane monooxygenase
  • Ribonucleotide reductase
  • Rubrerythrin

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology


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